MPEG:%20A%20Video%20Compression%20Standard%20for%20Multimedia%20Applications%20Didler%20Le%20Gall

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MPEGA Video Compression Standardfor Multimedia
ApplicationsDidler Le Gall
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Goals

• Reduce the high cost of video compression codecs
• Resolve the critical problem of interoperability
  of equipment from different manufacturers
• Come up with a standard within 2 years

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MPEG

• Stands for Moving Picture Experts Group (ISO-IEC)
• Started in 1988
• Had to come up with a draft of the standard by
  1990
• Received MPEG Proposal from mostly commercial
  companies

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MPEG (contd)

• MPEG-Video
• MPEG-Audio
• MPEG-System
• Synchronization of audio and video

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Requirements

• A Generic Standard
• Random Access
• Fast Forward/Reverse Searches
• Reverse Playback
• Audio Visual Synchronization
• Robustness to Errors

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Requirements (contd)

• Coding/Decoding Delay
• Editability
• Format Flexibility
• Cost Tradeoffs

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MPEG-VIDEO Compression

• Spacial Redundancy
• Intraframe compression
• DCT compression
• Temporal Redundancy (i.e. motion compression)
• Interframe compression

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Discrete Cosine Transform (DCT)
0 black 255 white
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DCT (contd)

• The 64 (8 x 8) DCT basis functions
• Superimpose multiples of these functions to
  simulate the original picture

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DCT (contd)
0 black 255 white
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DCT (contd)
700 90 90 -89 0 100 0 0 0 .... 0
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Motion Compensation

• I-Frame
• Independently reconstructed
• P-Frame
• Forward predicted from the last I-Frame or
  P-Frame
• B-Frame
• forward predicted and backward predicted from the
  last/next I-frame or P-frame

Transmitted as - I P B B B P B B B
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Motion Prediction
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Motion Estimation
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Motion Estimation (contd)
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Conclusion

• Video quality better than VHS can be achieved
  with a bit rate of about 1.5 Mbits/s
• Does not handle higher resolution with small bit
  rate

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References

• MPEG Notes by Dale Kolosna
• MPEG Compression Technique (http//rnvs.informatik
  .tu-chemnitz.de/jan/MPEG/HTML/mpeg_tech.html)